Medical imaging is a technique and process used to obtain images of the inside of a body for clinical analysis and medical intervention. It is used to reveal the internal structures hidden by the skin and bones, as well as to diagnose and treat diseases.
These techniques include x-rays, computed tomography (CT) and magnetic resonance tomography (MRI). These imaging tools allow the doctor to look inside the body to get an image of bones, organs, muscles, tendons, nerves, and cartilage.
This is one way the doctor can determine if there are any abnormalities. Imaging also describes various techniques for visualizing the inside of the body to help determine the causes of illness or injury and confirm a diagnosis. Doctors use it to see how well a patient's body responds to treatment for a fracture or illness. Magnetic resonance imaging can provide information about how the body works in real time.
This can help doctors find small obstructions or defects in the heart. An ultrasound uses high-frequency sound waves to take pictures of the inside of the body. The scan is performed by applying a water-based gel and then sliding a transducer over the area to be scanned. The transducer sends sound waves to the body and then receives the resonant waves to form an image.
An ultrasound is usually used during pregnancy, but it can also detect and diagnose conditions that affect the organs and soft tissues of the body. Medical imaging seeks to establish a database of normal anatomy and physiology to enable the identification of abnormalities. While imaging of removed organs and tissues can be performed for medical reasons, these procedures are generally considered part of pathology rather than medical imaging. Measurement and recording techniques that are not primarily designed to produce images, such as electroencephalography (EEG), magnetoencephalography (MEG), electrocardiography (ECG) and others, represent other technologies that produce data that can be represented as a graph of parameters compared to time or maps that contain data on measurement locations. In a limited comparison, these technologies can be considered forms of medical imaging in another discipline of medical instrumentation. Medical imaging is often perceived to refer to the set of techniques that produce non-invasive images of the internal appearance of the body.
In this restricted sense, medical imaging can be seen as the solution of inverse mathematical problems. This means that the cause (the properties of living tissue) is deduced from the effect (the observed signal). In the case of medical ultrasound, the probe consists of ultrasonic pressure waves and echoes that go inside the tissue to show the internal structure. In the case of projection radiography, the probe uses X-ray radiation, which is absorbed at different rates by different types of tissues, such as bones, muscles and fat. The term non-invasive is used to denote a procedure in which no instrument is inserted into a patient's body, as is the case with most of the diagnostic imaging techniques used. In the clinical context, medical imaging with invisible light is generally equated to radiology or clinical imaging.
Medical images with visible light include digital video or still images that can be viewed without special equipment. Dermatology and wound care are two modalities that use visible-light imaging. The interpretation of medical images is generally performed by a doctor specializing in radiology known as a radiologist; however, it can be performed by any health professional who is trained and certified in clinical radiological evaluation. Interpretation is being performed by more and more people who are not doctors; for example, radiographers are often trained in interpretation as part of an expanded practice. Diagnostic radiography refers to the technical aspects of medical imaging and, in particular, the acquisition of medical images. The radiographer (also known as a radiological technologist) is usually responsible for acquiring diagnostic quality medical images; although other professionals may be trained in this area, in particular, some radiological interventions performed by radiologists are performed without a radiographer. Two forms of radiographic imaging are used in medical imaging: projection radiography and fluoroscopy, with fluoroscopy being useful for guiding catheters.
These 2D techniques are still widely used despite advancements in 3D tomography due to their low cost, high resolution and lower doses of radiation with 2D techniques. This type of diagnostic imaging uses a wide beam of X-rays for image acquisition and is one of the first imaging techniques available in modern medicine. Nuclear medicine encompasses both diagnostic imaging and treatment for diseases; it may also be referred to as molecular medicine or molecular imaging and therapeutics. Nuclear medicine uses certain properties of isotopes and energetic particles emitted by radioactive material to diagnose or treat various pathologies. Unlike anatomical radiology, nuclear medicine allows physiology to be evaluated; this role-based approach has useful applications in most subspecialties, especially oncology, neurology and cardiology. Gamma cameras and PET scanners are used for scintigraphy, SPECT and PET scans to detect regions of biological activity that may be associated with disease. A relatively short-lived isotope such as 99mTc is administered to patients; isotopes are usually preferentially absorbed by biologically active tissue and can be used to identify tumors or fracture points in bones. The images are acquired after collimated photons are detected by a crystal that emits a light signal which is then amplified and converted into counting data.
Photoacoustic imaging is a recently developed hybrid form of biomedical imaging based on photoacoustic effect; it combines optical absorption contrast with ultrasonic spatial resolution for deep images in diffusive or quasidiffusive regimes. Recent studies have demonstrated that photoacoustic images can be used in vivo for monitoring tumor angiogenesis, mapping blood oxygenation, obtaining functional brain images and detecting cutaneous melanoma among other applications. FNIR is a relatively new non-invasive imaging technique.